feat: Add new env to support -o flag

[cloudxxx8]

Since the flag is hard to use for the container environment, create a new env EDGEX_OVERWRITE_CONFIG to provide the same feature support as -o/--overwrite flag.

Close #747

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PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?)
• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
• I have opened a PR for the related docs change (if not, why?)

Testing Instructions

1. Start the EdgeX with the default configs and config provider.
2. Modify the docker-compose file with the environment variable EDGEX_OVERWRITE_CONFIG: true and set other environment variable to change the private or common config.
3. Check the config provider if the new change of the environment variable overwrite is pushed.

[jinlinGuan]

LGTM